Date   

Re: AGC circuit to try?

Jerry Gaffke
 

Allison said:
>  If you feel that is not enough agc range then add the same mod at R35

That should probably be R33, not R35

I have no idea what the capacitance of a slightly forward biased 1n400x is,
figure 6 here suggests it's north of 30pf:  https://www.vishay.com/docs/88503/1n4001.pdf
Might be marginal at 45mhz, can vary wildly with diode type and brand.

Consensus seems to be that a 1n4007 is preferred over other 1n400x flavors for use as a PIN.
Some experimentation may be required using diodes from different manufacturers:
    https://groups.io/g/BITX20/message/32099
That entire thread is worth looking over.

If you are paying $5 postage to ship in some 1n4007's, you might consider
also getting some BAP64-02's at $0.43 each single unit pricing, Mouser 771-BAP64-02-T/R.
Down to $0.10 or so if you buy a reel.
Fully spec'd for use as an RF PIN diode. 
We've discussed the BAP64Q array of four PIN diodes in the forum previously
for use as a (roughy) 50 ohm conrolled impedance bridge attenuator.
Easily searched for on the forum website.

Jerry, KE7ER


On Sat, Apr 7, 2018 at 12:15 pm, ajparent1 wrote:
You have the audio detection to get an AGC control voltage but you don't show what your controlling.

What I find odd in general every one seems to be bent on leveling the audio volume in the audio circuit.
Why?  I understand protecting ones ears and all but what an audio compressor?  

The Bitx or uBitx has enough gain and handy places that RF gain control based on audio detection works
very well.  The easy way is replace R13 (ubitx) with a diode such as 1n400x (x=1 to 7) and controlling the
current through the diode to make it behave as a variable resistance at RF.  

The current would be about 4-6ma at max gain and decrease to zero (0) at minimum gain.  For that design
the AGC range is about 26 to 32db depening on band.  If you feel that is not enough agc range then add
the same mod at R35 then with both the agc range is near 60+ DB, generally enough.  AGC in this form
is less prone to overload distortion as you are lowering gain.  The control could be a pot between 8V
(or RX-V) and ground and a series 1K resistor to the he diode (x2 of your using both diodes).  That is a
manual gain control.   To make it automatic use a circuit like just published to detect the voltage at the
top of the audio gain pot and feed that voltage to the gain control diodes.  The circuit should be
arranged to put 4-8V out at NO Audio and decrease to zero volts with increasing audio.

Side note the 1n400x series with minor reservations makes a fine substitute for a PIN diode, the
prefered but more costly device for this function.  Beside being widely available and cheap
( I buy them in quantities of 100 for pennies each) makes it useful.  It also makes a good
20pf varicap and a 1A rectifier to 1000V (1n4007).

This was tested on the first bitx20 I built over a decade ago to test AGC and is used on several  older Tentec
radios and more than few of my own design.   That said its far from a new idea or design as its documented
in EMRFD and the older SSD (Solid State Design AARL press, out of print).   


Re: RadioKits.in Case #ubitx

lou_w2row
 

I also had trouble fitting the power pcb between the fuse and switch. I bent the fuse lead so that it sort of fit together. My switch survived the soldering but just barely. I could see the plastic softening.

Has anyone tried to fit the tuning knob (provided with the case) to the encoder (provided with the radio)? The hole in the knob is much to small to fit on the encoder shaft. I could not see anyway to adjust the knob opening.

73,  Lou W2ROW


Re: AGC circuit to try?

Gordon Gibby <ggibby@...>
 

​Allison --- THanks VERY VERY much for that informative post about using a 1n400X diode as a rf gain control!!!!


Gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of ajparent1 <kb1gmx@...>
Sent: Saturday, April 7, 2018 3:15 PM
To: BITX20@groups.io
Subject: Re: [BITX20] AGC circuit to try?
 
It is incomplete..

You have the audio detection to get an AGC control voltage but you don't show what your controlling.

What I find odd in general every one seems to be bent on leveling the audio volume in the audio circuit.
Why?  I understand protecting ones ears and all but what an audio compressor?  

The Bitx or uBitx has enough gain and handy places that RF gain control based on audio detection works
very well.  The easy way is replace R13 (ubitx) with a diode such as 1n400x (x=1 to 7) and controlling the
current through the diode to make it behave as a variable resistance at RF.  

The current would be about 4-6ma at max gain and decrease to zero (0) at minimum gain.  For that design
the AGC range is about 26 to 32db depening on band.  If you feel that is not enough agc range then add
the same mod at R35 then with both the agc range is near 60+ DB, generally enough.  AGC in this form
is less prone to overload distortion as you are lowering gain.  The control could be a pot between 8V
(or RX-V) and ground and a series 1K resistor to the he diode (x2 of your using both diodes).  That is a
manual gain control.   To make it automatic use a circuit like just published to detect the voltage at the
top of the audio gain pot and feed that voltage to the gain control diodes.  The circuit should be
arranged to put 4-8V out at NO Audio and decrease to zero volts with increasing audio.

Side note the 1n400x series with minor reservations makes a fine substitute for a PIN diode, the
prefered but more costly device for this function.  Beside being widely available and cheap
( I buy them in quantities of 100 for pennies each) makes it useful.  It also makes a good
20pf varicap and a 1A rectifier to 1000V (1n4007).

This was tested on the first bitx20 I built over a decade ago to test AGC and is used on several  older Tentec
radios and more than few of my own design.   That said its far from a new idea or design as its documented
in EMRFD and the older SSD (Solid State Design AARL press, out of print).   


Allison


Re: AGC circuit to try?

ajparent1 <kb1gmx@...>
 

It is incomplete..

You have the audio detection to get an AGC control voltage but you don't show what your controlling.

What I find odd in general every one seems to be bent on leveling the audio volume in the audio circuit.
Why?  I understand protecting ones ears and all but what an audio compressor?  

The Bitx or uBitx has enough gain and handy places that RF gain control based on audio detection works
very well.  The easy way is replace R13 (ubitx) with a diode such as 1n400x (x=1 to 7) and controlling the
current through the diode to make it behave as a variable resistance at RF.  

The current would be about 4-6ma at max gain and decrease to zero (0) at minimum gain.  For that design
the AGC range is about 26 to 32db depening on band.  If you feel that is not enough agc range then add
the same mod at R35 then with both the agc range is near 60+ DB, generally enough.  AGC in this form
is less prone to overload distortion as you are lowering gain.  The control could be a pot between 8V
(or RX-V) and ground and a series 1K resistor to the he diode (x2 of your using both diodes).  That is a
manual gain control.   To make it automatic use a circuit like just published to detect the voltage at the
top of the audio gain pot and feed that voltage to the gain control diodes.  The circuit should be
arranged to put 4-8V out at NO Audio and decrease to zero volts with increasing audio.

Side note the 1n400x series with minor reservations makes a fine substitute for a PIN diode, the
prefered but more costly device for this function.  Beside being widely available and cheap
( I buy them in quantities of 100 for pennies each) makes it useful.  It also makes a good
20pf varicap and a 1A rectifier to 1000V (1n4007).

This was tested on the first bitx20 I built over a decade ago to test AGC and is used on several  older Tentec
radios and more than few of my own design.   That said its far from a new idea or design as its documented
in EMRFD and the older SSD (Solid State Design AARL press, out of print).   


Allison


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

K9HZ <bill@...>
 

Ya know this is really easy to do with "#If defined" statements in just a
single sketch... if you uncomment a symbol like "#define I2C_Display" and
comment out the "#define Parallel_Display" (or vice versa) it could
automatically switch libraries... depending upon what print libraries are
used, the print/write calls are the same so those don't have to change.
Just the two variables.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Yahoo Group.

email:  bill@wjschmidt.com

-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim Gorman
Sent: Saturday, April 7, 2018 11:54 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Variation on Ian's KD8CEC uBitx software (based on his
1.04 release for now) and ATU sketch. #ubitx

Any chance of getting an option for an I2C display or a non-I2C display?

tim ab0wr

On Sun, 01 Apr 2018 01:19:47 -0700
"John" <passionfruit88@hotmail.com> wrote:

I have implemented the following changes in this software targeted at
/P, /PM operations (software is in the files section):
1. Options for various features which can be turned on or off. Key
objective is to be able to customise the rig based on your needs and
unfortunately on the restricted memory size of the Nano. So not all
features can be selected at once. Choices, choices... 2. ATU control.
A servo-based L-Network ATU. The communication between the Raduino and
the ATU Arduino is via I2C. There is a separate sketch for the ATU
Arduino (Nano or Pro-mini). ATU operating mode can be set to OFF,
Manual as in on-demand, or auto-RX meaning that it pre-tunes based on
historical data on a change of band and after first change of dial
frequency (for a quick scan of the bands). It uses the EEPROM data of
the closest stored frequency for pre-tune or tune on-demand to
accelerate the tuning process. 3. Handsfree microphone/headphone.
Using an Android style 3 rings (TTRS) handsfree earpieces/mic
combination, with 1 or 3 buttons (Play/Pause, +, -), the PTT is
controlled by Play/Pause as toggle, and I use long presses on + and -
as respectively pre-tune and smarttune of the ATU. Short + or -
presses could be used for frequency up and down. Requires a very
simple hardware mod to free-up A6 (see below). 4. SWR measure and
display, using analogue input A7 from an 2N7002 based AGC or a
MAX9814 circuit or any other for that matter. 5. Software based AGC
range extender to augment (as in double or triple) the dynamic range
of an audio AGC. This uses the slope of the 1st If filter at 45Mhz to
attenuate the Rx signal when the audio AGC reaches its limit. Adds
over 50dB of dynamic range. 6. Forward power and SWR measure and
display. Currently assumes that th ATU is providing that info over
I2C. Otherwise could be adapted with a pair of analogue inputs for
measure. See the excellent NT6D design on the wiki. 7. An option to
display the S-Meter, SWR and forward power in either easy to see "fat"
bars with no number, or "skinny" bars with more text and numbers. 8.
An option to enable a "Memory mode", selectable by menu, which cycles
through all the populated memories (channels). Dial lock also locks
the change of channels. 9. Made some rarely used or once-off functions
as options to recover program memory after initial tuning and allow
for more options to be selected. 10. Fixed some issues with the
IF-shift option. Ian has resolved these in his new
V1.06 and later releases. Two issues were present: IF-shift in USB
would change the receive frequency and it was applied to TX as well.
Now applies to Rx only. The only required hardware mod is to connect
the CW key input to the PTT. Since in Ian's software we select the
mode by menu, there is no need to have a separate analogue input
tied-up for the CW key. This frees-up analogue input 6 for use by
other functions like the handsfree option above. To-Do: apply Ian's
improvements in 1.06, especially CW transmit frequency option and if
possible the WSPR beacon mode. Usage: download the zip files, unzip in
your Arduino sketches folder. Edit the ubitx_20 options sections,
using #define for enabled and #undef for disabled. Perform a CTRL-R to
compile and check how much memory is used. If you go over the limit, a
warning is issued. Upload to the Arduino.

I have uploaded both the Raduino as well as the Arduino sketch for the
ATU and SWR measurement. They can be found in the folder "Variations
on Ian Lee's Software (by VK2ETA) + ATU sketch". All software in under
GPL V3.
All the best,

73, John (VK2ETA)




---
This email has been checked for viruses by AVG.
http://www.avg.com


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

Tim Gorman
 

Any chance of getting an option for an I2C display or a non-I2C display?

tim ab0wr

On Sun, 01 Apr 2018 01:19:47 -0700
"John" <passionfruit88@hotmail.com> wrote:

I have implemented the following changes in this software targeted
at /P, /PM operations (software is in the files section):
1. Options for various features which can be turned on or off. Key
objective is to be able to customise the rig based on your needs and
unfortunately on the restricted memory size of the Nano. So not all
features can be selected at once. Choices, choices... 2. ATU control.
A servo-based L-Network ATU. The communication between the Raduino
and the ATU Arduino is via I2C. There is a separate sketch for the
ATU Arduino (Nano or Pro-mini). ATU operating mode can be set to OFF,
Manual as in on-demand, or auto-RX meaning that it pre-tunes based on
historical data on a change of band and after first change of dial
frequency (for a quick scan of the bands). It uses the EEPROM data of
the closest stored frequency for pre-tune or tune on-demand to
accelerate the tuning process. 3. Handsfree microphone/headphone.
Using an Android style 3 rings (TTRS) handsfree earpieces/mic
combination, with 1 or 3 buttons (Play/Pause, +, -), the PTT is
controlled by Play/Pause as toggle, and I use long presses on + and -
as respectively pre-tune and smarttune of the ATU. Short + or -
presses could be used for frequency up and down. Requires a very
simple hardware mod to free-up A6 (see below). 4. SWR measure and
display, using analogue input A7 from an 2N7002 based AGC or a
MAX9814 circuit or any other for that matter. 5. Software based AGC
range extender to augment (as in double or triple) the dynamic range
of an audio AGC. This uses the slope of the 1st If filter at 45Mhz to
attenuate the Rx signal when the audio AGC reaches its limit. Adds
over 50dB of dynamic range. 6. Forward power and SWR measure and
display. Currently assumes that th ATU is providing that info over
I2C. Otherwise could be adapted with a pair of analogue inputs for
measure. See the excellent NT6D design on the wiki. 7. An option to
display the S-Meter, SWR and forward power in either easy to see
"fat" bars with no number, or "skinny" bars with more text and
numbers. 8. An option to enable a "Memory mode", selectable by menu,
which cycles through all the populated memories (channels). Dial lock
also locks the change of channels. 9. Made some rarely used or
once-off functions as options to recover program memory after initial
tuning and allow for more options to be selected. 10. Fixed some
issues with the IF-shift option. Ian has resolved these in his new
V1.06 and later releases. Two issues were present: IF-shift in USB
would change the receive frequency and it was applied to TX as well.
Now applies to Rx only. The only required hardware mod is to connect
the CW key input to the PTT. Since in Ian's software we select the
mode by menu, there is no need to have a separate analogue input
tied-up for the CW key. This frees-up analogue input 6 for use by
other functions like the handsfree option above. To-Do: apply Ian's
improvements in 1.06, especially CW transmit frequency option and if
possible the WSPR beacon mode. Usage: download the zip files, unzip
in your Arduino sketches folder. Edit the ubitx_20 options sections,
using #define for enabled and #undef for disabled. Perform a CTRL-R
to compile and check how much memory is used. If you go over the
limit, a warning is issued. Upload to the Arduino.

I have uploaded both the Raduino as well as the Arduino sketch for
the ATU and SWR measurement. They can be found in the folder
"Variations on Ian Lee's Software (by VK2ETA) + ATU sketch". All
software in under GPL V3.
All the best,

73, John (VK2ETA)


Re: AGC circuit to try?

Kees T
 

Any comments on using a H11F3M MOSFET Optocoupler as the AGC on the uBITX. One of their applications shows an "Audio AGC" circuit. Seems quite simple and easy to implement here.

73 Kees K5BCQ


Re: KD8CEC software user manual

Bill KC5SB
 

Excellent!  Thanks!


Re: Tuning with Si5351 and Rotary encoders

Pradeep Kumar
 

Hi Jack,

I have the same bitx40 with pot tuning , just wanted to make it to rotary , did you finally managed to correct the code ? , if yes does that straightway goes into that Si5351 control board ? Do you mind sharing the code with me please ?

73,
Pradeep vu3edg


Re: KD8CEC software user manual

Tom Christian
 

Great job, Rod!  Very good manual & much needed! 
Thank you!
Tom
AB7WT


Re: uBITX shipping time

Terry Morris
 

Sounds right. My delivery was 11 weeks from order date. When I read about the stoppage due to toroid shortage/no-supply I guesstimated longer. Communication on this list kept me informed.


Terry - KB8AMZ
Brimfield Twp, OH  USA
Linux User# 412308, Ubuntu User# 34905
OSs: LM18.2 64bit, Ubuntu 16.04, tahrPup64 64bit, Raspian
Orgs: PCL70-FOP, NTHS, ALUG, ARRL, PCARS#78, NAQCC#6668, NO-QRP-C, QRP-ARCI#8855, SKCC#14195, USN 1965-1969 AG3

I chair the PCARS CW/QRP SIG and Linux for Hams SIG, second and fifth Tuesday

my computer, my opinion

On Fri, Apr 6, 2018 at 9:22 AM, David Robertson <kd1na363@...> wrote:
Yesterday I got a notification from Paypal that my uBITX kit was shipped. I ordered the kit around the 10th of February. It appears that there is an approximately a 2 month delay when you order to when the kit is shipped. Just thought this information is helpful.
73 Dave KD1NA 



Re: RadioKits.in Case #ubitx

Mike Yancey
 

https://amateurradiokits.in/store/metal-enclosures/

...but I believe the demand has been such that they're on hold until April 15.
Some, or all, might be 'out of stock' for now.

Mike Yancey, KM5Z
Dallas, Texas, USA


Re: AGC circuit to try?

Paul Galburt - K2AYZ
 

BTW, is there a way to edit posts once submitted? I would like to make a minor change but don'ts see a tool for that.


Re: AGC circuit to try?

Paul Galburt - K2AYZ
 

This circuit is an audio envelope detector - it provides a dc voltage that corresponds to its input audio voltage. This is then applied as a gain control signal to a "voltage controlled amplifier" of VCA (the audio path) that is not shown. There are several solutions to implementing a good VCA, not all are trivial.

This sort of detection can be used to implement a "feed forward" AGC which effective "programs" the gain reduction based on the input level, or a "feed back" or closed loop AGC which acts to prevent the VCA output from exceeding some threshold. Each method has advantages and disadvantages. Which this particular usage is cannot be determined without seeing more of the circuit.

Hope this helps,

Paul K2AYZ


Re: RadioKits.in Case #ubitx

Paul Galburt - K2AYZ
 

John, could you point me at the website for the case?

73, Paul K2AYZ


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

John <passionfruit88@...>
 

This should work well Hidheiko-san.

73, John


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

Hidehiko Komachi - JA9MAT
 

TKS John,
OK all about how to activate the S-Meter.
Well I will try the AGC voltage from MAX9814 MIC AMP Board you introduced before. And I've ordered to eBay as blow URL;
https://www.ebay.com/itm/Electret-Microphone-Amplifier-MAX9814-Adjustable-Gain-Breakout-Board-4-Pins/232405145745?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
Thanks again 73.

ja9mat Hidheiko.

 


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

John <passionfruit88@...>
 

Hello Hidheiko-san,

The S-Meter display needs to read the level  of AGC or an audio level from pin A7 on the Raduino (the unused pin on the Raduino connector).

In the program it is shown in file ubitx_20.ino as:

//To read the AGC voltage on the MAX9814
#define ANALOG_SMETER (A7)

An example of a circuit that would give you a signal strength value is shown in the diagram below, using the 2nd audio amplifier channel of the TDA2822. I show in the blue part what is required.



This was part of the pre-production uBitx diagram but was not implemented in the production version.

The 2N7002 is used as an automatic gain control and can be used or not for that application. 

You would need to insert a trim-potentiometer (10KOhms is good) between ping 6 of the TDA2822 and the VOL-H connection to adjust the sensitivity, plus (VERY IMPORTANT) a voltage divider between the kathode of the diode and the ground to limit the voltage to under 5VDC for the analogue input of the Raduino. I would use 330KOhms in series with 100KOhms to the ground, and connect A7 to the junction of the twe resistors. Tell me if you need me to draw a full diagram.

Further adjustments are available in the software if required as we define the 9 stages of the S-meter display (first stage is zero, then 6 stages for growing bars, 1 stage showing "+" and one stage showing the custom "++" symbol). In ubitx_20.ino  it shows as:

int sMeterLevels[] = {0, 5, 17, 41, 74, 140, 255, 365, 470};
 
The values in the array are the measured values on the analogue input (defined as A7 above) at which we step into a higher "stage" and can go from zero for zero volts to 1023 for a 5V DC value. 

Hope this helps Hidheiko-san,

73, John (VK2ETA)


Re: KD8CEC software user manual

Carlos E. Wenzel <Ik2yra@...>
 

Mni tks Rod!!!

73's de IK2YRA

2018-04-06 19:09 GMT+02:00 wishbone_aaa <dlmock@...>:

Thank you for a job well done.  Just received my ubitx and this is the information that I was seeking.  Much appreciated .  73






--
Carlos Wenzel
ik2yra@...
+39-3284684518
Skype: IK2YRA


Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

Hidehiko Komachi - JA9MAT
 

Hello John,
Thanks for tour modified firmware. Well I tried the latest version and had a success with uploading arduino. I can see the S_ meter display but its level up to maximum and I can not hear anything. Is AGC masking the signal?

ja9mat Hidheiko.